High-quality CoP nanorings (CoP NRs) are easily achieved by phosphorating treatment of CoOOH nanorings, which reveal high activity towards hydrogen evolution reaction and nitrate electrocatalytic reduction reaction due to substantial...

The sluggish reaction kinetics of the anodic oxygen evolution reaction increases the energy consumption of the overall water electrolysis for high-purity hydrogen generation. In this work, ultrathin cobalt sulfide nanosheets (Co3S4-NSs) on nickel foam (Ni-F) nanohybrids (termed as Co3S4-NSs/Ni-F) are synthesized using cyanogel hydrolysis and a sulfurization two-step approach. Physical characterizations reveal that Co3S4-NSs with a 1.7 nm thickness have abundant holes, implying the big surface area, abundant active edge atoms, and sufficient active sites. Electrochemical measurements show that as-synthesized Co3S4-NSs/Ni-F have excellent electrocatalytic activity and selectivity for ethanol oxidation reaction and hydrogen evolution reaction. Due to their bifunctional property of Co3S4-NSs/Ni-F nanohybrids, a symmetric Co3S4-NSs/Ni-F∥Co3S4-NSs/Ni-F ethanol electrolyzer can be effectively constructed, which only requires a 1.48 V electrolysis voltage to reach a current density of 10 mA cm–2 for high-purity hydrogen generation at the cathode as well as value-added potassium acetate generation at the anode, much lower than the electrolysis voltage of traditional electrochemical water splitting (1.64 V).

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Holey CoOOH nanosheets (CoOOH HNSs) are easily synthesized by a successive coordination–oxidation–hydrolysis strategy.

The electrocatalytic nitrate reduction reaction (NO 3 − -ERR) to ammonia (NH 3 ) is a promising strategy for NH 3 production. Cu-based nanomaterials have been regarded as a kind of effective NO 3 − -ERR catalysts. In this work, high-quality hollow Cu 2 O nanocubes (Cu 2 O h-NCs) are facilely synthesized by a simple one-step reduction method. The as-prepared Cu 2 O h-NCs reveal high selectivity and activity for NO 3 − -ERR, which is ascribed to abundant oxygen vacancies, high surface area, hollow architecture, low mass transfer resistance, and strong adsorbing ability toward NO 3 − . In fact, Cu 2 O h-NCs can achieve a Faradic efficiency of 92.9% and an NH 3 yield of 56.2 mg h −1 mg cat −1 for NH 3 production at −0.85 V (vs RHE) potential, which exceeds those of other transition-metal-based NO 3 − -ERR electrocatalysts.